The experiments in this proposal are designed to continue investigations into neuronal processes controlling dopamine modulation of responses mediated by activation of glutamate and GABA receptors in the striatum. The first two aims are a direct continuation of studies begun in the presently funded proposal and will examine the hypothesis that the direction of DA modulation of responses mediated by activation of glutamate receptors is a function of the subtype of glutamate receptor activated and the subtype of DA receptor activated. The third aim is new and will examine the hypothesis that the direction of DA modulation of responses mediated by activation of GABA-A receptors is a function of the DA receptor subtype activated, its site of location on pre- and/or postsynaptic elements and the type of neuron.